Multi-position character display panel

ABSTRACT

THE DISPLAY PANEL IS GAS-FILLED AND INCLUDES A PLURALITY OF CHARACTER POSITIONS. THE PANEL IS OF A SANDWICH CONSTRUCTION AND INCLUDES A BASE PLATE ON WHICH A PLURALITY OF GROUPS OF CATHODES AND THEIR CONDUCTORS OR LEADS ARE FORMED. THE CATHODES ARE IN THE FORM OF BARS OR SEGMENTS AND CAN DISPLAY A CHARACTER. THE CATHODES ARE COATED WITH A LAYER OF MERCURY TO PREVENT SPUTTERING DURING NORMAL OPERATION. THE PANEL ALSO INCLUDES AN ANODE ELECTRODE FOR EACH GROUP OF CATHODES AND A FACE PLATE, SPACED FROM THE BASE PLATE.   D R A W I N G

s. A. KUPSKY 3,?20A52 MULTI-POSITION CHARACTER DISPLAY PANEL 2 Sheets-Sheet B H, mm

Filed March is, 1971 Fig. 2

INVENTOR. George A. Kupsky ATTORNEY United States Patent O 3,720,452 MULTI-POSITION CHARACTER DISPLAY PANEL George A. Kupsky, Milford, N..I., assignor to Burroughs Corporation, Detroit, Mich. Filed Mar. 16, 1971, Ser. No. 124,681 Int. Cl. H01j 7/38 US. Cl. 316-24 2 Claims ABSTRACT OF THE DISCLOSURE The display panel is gas-filled and includes a plurality of character positions. The panel is of a sandwich construction and includes a base plate on which a plurality of groups of cathodes and their conductors or leads are formed. The cathodes are in the form of bars or segments and can display a character. The cathodes are coated with a layer of mercury to prevent sputtering during normal operation. The panel also includes an anode electrode for each group of cathodes and a face plate, spaced from the base plate.

BACKGROUND OF THE INVENTION atmosphere, and generally, the mercury has been intro- 3 dueed from a capsule held within the display device and released therefrom at a selected time in the manufacturing process. Although this method and arrangement for providing mercury in a display device has been used satisfactorily for many years, it is always desirable to provide improvement, and such improvement is achieved through the present invention.

SUMMARY OF THE INVENTION Briefly, a display device embodying the invention includes a base plate carrying a plurality of groups of cathode electrodes and an anode for each group of cathodes. The cathode electrodes are directly coated with a film of mercury to minimize cathode sputtering.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective exploded view of a display panel embodying the invention; and

FIG. 2 is a sectional view, along the lines 2-2, in FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The display panels described herein are thin, flat, sheetlike members which may have substantially any desired size and shape, and may include substantially any number of character display positions. The panels may also include any suitable ionizable gas such as neon, argon, xenon, etc., singly or in combination. A wide range of gas pressures may be used, for example, from about 20 to about 350 torr or higher at ambient temperature, with about 75 torr being a pressure which is commonly and conveniently used.

The principles of the invention are applicable to many types of cold cathode display devices, and the display panel shown and described herein is a segment-type device which includes an insulating base plate of glass,

3,720,452 Patented Mar. 13, 1973 ceramic, or the like which carries, on its top surface, a plurality of narrow conductive leads or runs 30 (A to G). The runs 30 are parallel to each other and aligned with the horizontal axis of the base plate. Seven runs 30A to 30G are shown; however, more or fewer may be provided, the number being determined by the total number and type of characters to be displayed. The runs 30 may be formed by an evaporation process, a silk-screen process, an electroless plating process, are plasma spraying, flame spraying, or the like, or they may be discrete strips of metal, heat sealed or otherwise secured to'the insulating plate 20. A silk-screen printing process is particularly suitable because it is fast, efficient, and reproducible.

A thin layer 40 of insulating material such as glass or ceramic is provided on the conductive runs 30, preferably by a silk-screen or spraying process. The layer 40 is provided with a plurality of groups of apertures 50A to 506, each aperture exposing one of the runs 30A to 30G. Thus, each group of apertures includes aperture 50A which exposes run 30A, aperture 50B which exposes run 30B, aperture 50C which exposes run 30C, etc.

Panel 10 also includes a group of cathode electrodes 60 (A to G) for each group of apertures 50; the cathodes are generally fiat elongated bars or segments, and they are generally arrayed in a figure 8 pattern, as is well known in the art. The cathodes 60 may be formed by any of the processes mentioned above with a silk-screen process or the like performed with a conductive paste such as palladium-gold, platinum-gold, palladium-silver, or the like. Each cathode element fills its aperture 50, is in direct contact with one of the runs 30 exposed thereby, and covers a portion of the top surface of layer 40 to achieve the desired shape and size for each cathode.

The cathodes 60 may also be formed of discrete strips of metal, each of which is brazed to a conductive run 30 by means of a mass of brazing material deposited in each of the apertures 50 in the insulating layer 40. The brazing material may also be deposited by a silk-screen process or the like, with one suitable brazing material being a gold-germanium substance known as Formon which is sold by Du Pont.

According to the invention, each cathode electrode is coated with a film or layer 86 (FIG. 2) of mercury formed in any suitable manner, with one method being described below.

Panel 10 also includes an anode electrode 90 for each group of cathode electrodes 60. The anode electrodes 90 comprise transparent conductive films of gold, NESA, or the like deposited on the lower surface 96 of the panel face plate or viewing plate 100 which is made of glass. The anode films 90 are generally rectangular in shape, or they are otherwise shaped, depending on the orientation of the cathodes, and they are dimensioned and positioned so that they overlay the area defined by each group of cathode electrodes, as illustrated in FIG. 2. The anodes thus face the fiat surfaces of the cathodes, and these sur faces generate cathode glow areas of the same general shape in operation of the panel.

Alternatively, the anode electrodes may comprise separate screens (not shown) suitably supported above the groups of cathode electrodes. This type of anode is shown in copending application S.N. 55,388, filed July 16, 1970.

The top glass cover plate 100 is spaced from the base plate 20 by a rectangular frame member which may be integral with cover plate 100, or it may be a separate piece which is disposed between the top glass plate 100 and the insulating layer 40. The rectangular frame 110 serves to provide the desired spacing between each anode and its associated group of cathode electrodes.

The three glass members 20, 100, and 110 are sealed together by means of an hermetic seal (FIG. 2)

formed along the adjacent edges of the members by means of a glass frit or the like.

Suitable contact pins 122 are secured to the cathode runs 30, and contacts 124 are also made to anodes 90, and all contacts are embedded in seal 120.

The panel is filled with the desired gas atmosphere through a tubulation 150 secured to the base plate and communicating with the interior of the panel through a hole 160 in base plate 20.

As noted, the cathodes are coated with a film of mercuiy 86, and this is achieved, in one method, by providing a small ball of mercury in a side arm connected to tubulation 150, through which the slected gas is introduced into the panel and which communicates with the interior of the panel through holes 160 and 170 in plate 20 and film 40, respectively. At a selected time in the process of manufacturing the panel and after the panel has been filled with its gas and the tubulation has been removed below side arm 140 and sealed as at 144, the panel is inverted and tilted to cause the ball of mercury 130 to move from the side arm 140 into the tubulation and through holes and into the panel. The panel is then turned right-side-up, and it is suitably tilted back and forth to cause the mercury ball to move back and forth over the surfaces of the cathodes, and, as the mercury contacts the cathodes, it is theorized that amalgam or amalgam-like films 86 form on the cathodes. Then the unamalgamed or otherwise unattached mercury residue is removed through hole 160 if this is mechanically feasible; however, in a preferred method, the panel is heated uniformly while the tubulation 150 is maintained at a somewhat lower temperature whereby the unamalgamated mercury is vaporized and dilfuses to and condenses in the tubulation 150. Finally, side arm 140 is removed, and the tubulation is sealed ofi? as at 146.

A display panel made according to the invention has cathodes 50 which resist sputtering, are especially uniform, and have long life, all because of their uniform coating of mercury.

What is claimed is:

1. Method of making a display device comprising the steps of providing a plurality of generally fiat cathode electrodes in gas-filled envelope,

introducing a ball of mercury into said envelope, passing said ball of mercury over the cathode electrodes to coat the surfaces of said cathode electrodes with an adherent film of mercury, and

removing excess mercury from said envelope.

2. The method defined in claim 1 wherein said envelope has a tubulation outside said envelope and said last step of removing excess mercury is performed by heating said envelope to an elevated temperature while keeping said tubulation at a lower temperature whereby said excess mercury in said envelope is vaporized and condenses in said tubulation.

References Cited UNITED STATES PATENTS 3,366,820 l/l968 Wolfe 313174 X 2,991,387 7/1961 McCauley 3l3109.5 3,617,803 11/1971 Wheeler 313-1095 3,512,028 5/1970 McNaney 313109.5 3,478,243 11/1969 Bakker et a1. 313-1095 3,617,796 11/1971 Caras 3l3l09.5

HERMAN KARL SAALBACH, Primary Examiner S. CHATMON, JR., Assistant Examiner US. Cl. X.R. 

